1. Field of the Invention
The present invention relates to an electron-emitting device, an electron source comprising this electron-emitting device, and an image-forming apparatus such as a display to which the electron source is applied. More especially, it relates to a surface conduction electron-emitting device having a novel constitution, an electron source using this surface conduction electron-emitting device, and an image-forming apparatus such as a display to which the electron source is applied.
2. Related Background Art
A surface conduction electron-emitting device utilizes a phenomenon in which electron emission occurs by applying a current to an electroconductive film formed on a substrate.
As examples of this surface conduction electron-emitting device, there have been reported a device using an SnO2 thin film [M. I. Elinson, Radio Eng. Electron Phys., 10, 1290, (1965)], a device using an Au thin film [G. Ditmmer, Thin Solid Films, 9, 317 (1972)], a device using an In2O3/SnO2 thin film [M. Hartwell and C. G. Fonsted, IEEE Trans. ED Conf., 519 (1975)], and a device using a carbon thin film [Hisahi Araki et al., Sinku (Vacuum), Vol. 26, No. 1, 22 p., (1983)].
In these surface conduction electron-emitting devices, generally speaking, the state is set in which electron emission occurs by performing energization forming operation called xe2x80x9cformingxe2x80x9d to the above electroconductive film before performing the electron emission.
Here, xe2x80x9cformingxe2x80x9d indicates that the state is set in which electron emission occurs by applying a constant voltage or for example, a voltage which slowly rises at a rate of about 1 V per minute to both the ends of the above electroconductive film, applying a current to the above electroconductive film, locally damaging, deforming or deteriorating the above electroconductive film and making it enter an electrically high resistive state.
It is considered that a fissure is formed on a part of the above electroconductive film by this operation and the phenomenon of electron emission results from the existence of this fissure. Besides, it is not made clear completely that the actual electron emission occurs in which part, but the above fissure and its peripheral area may be called a xe2x80x9celectron-emitting regionxe2x80x9d for convenience.
This applicant has already advanced many proposals on a surface conduction electron-emitting device. For example, that it is desirable the above xe2x80x9cformingxe2x80x9d should be performed by applying a pulse voltage to an electroconductive film is disclosed in Japanese Patent No. 2,854,385, U.S. Pat. Nos. 5,470,265 and 5,578,897.
Here, for a pulse voltage waveform, both the method of maintaining a peak value constant, as shown in FIG. 5A, and the method of slowly increasing the peak value, as shown in FIG. 5B, are acceptable and can properly be selected considering the shape and material of a device and its forming conditions.
Further, immediately followed by the above forming, it is detected that both a current (device current If) applied to a device and a current (emission current Ie) caused by electron emission is increased by repeatedly applying a pulse voltage to an electron-emitting device under the atmosphere containing organic substances, and this operation is called xe2x80x9cactivationxe2x80x9d.
This operation forms a deposited film whose main component is carbon in the area containing the fissure formed on an electroconductive film by xe2x80x9cformingxe2x80x9d, and the details are disclosed in Japanese Patent Application Laid-Open No. 7-235255.
To adapt such surface conduction electron-emitting apparatus as described above to an image-forming apparatus, its low power consumption and high luminance are still more requested.
Consequently, it is requested as the performance of an electron-emitting device that the ratio of the emission current Ie to the device current If, i.e. the electron emission efficiency should be increased more than before.
An object of the present invention is to provide an electron-emitting device which is excellent in electron emission characteristics, an electron source which uses the electron-emitting device and an image-forming apparatus which uses the electron source.
The present invention is an electron-emitting device comprising a pair of conductors arranged on a substrate so as to face each other and a pair of deposited films whose main component is carbon which are arranged by being connected to a pair of these conductors and arranged by being caught in a gap, wherein silver is contained in the deposited film at a ratio of carbon within the range of 5 mol % or more and less than 10 mol %.
Further, the present invention is an electron-emitting device comprising a pair of device electrodes arranged on a substrate so as to face each other, an electroconductive film which is arranged by being connected to a pair of these device electrodes and has a fissure between a pair of the device electrodes and a deposited film whose main component is carbon which is formed on the area containing the inside of the fissure and the fissure and has a gap having a narrower width the fissure in the fissure, wherein silver is contained in the deposited film at a ratio of carbon within the range of 5 mol % or more and less than 10 mol %.